First. Btc crash.
It is a common understanding that when btc drop, altcoins drop but there is slightly more to it. Btc as the king of crypto has huge influence on cryptos since great majority of the altcoins are paired with btc . Whenever people wants to cash out of altcoins, they need to convert into btc or eth or ltc then cash it out from there. Thus, when btc in general crashes, all altcoins btc ratio will crash as well because people are selling off their altcoins to cash out which lead to btc crash. This crash is caused by political events regard to crypto market.
Secondly, Btc raises
Likewise when btc raises, means more money flowed into crypto market and plenty of these money too eventually will flow into the altcoins, leading to increase of btc ratio for altcoins. This boom is caused by political events regard to crypto market.
Third, Bitgrail lost 17m nano to alleged hacks.
A group of people will panic sell, believing in the alleged hacks therefore possibility of 17m being dumped onto market
A group of people will spread fuds and cause more to sell
A group of people will know the above two will cause price drop so they will too sell to re-enter at low price
Forth, end of corrections.
When price changes with little despite having decent for half a day, it indicate the end of correction.
Fifth, altcoin update
Long awaited update is delivered while assuring more to come, boosting confidence for the altcoin development.